Electron dynamics in dimerization process

We first survey the relaxation of electronic structure in the dimerization process of two FAMs to the stable FAD. To do so, we study the difference density in the spatial distribution of one electron density [483] between FAD and two FAMs Suppose that there is a FAD at a given geometry. Then we assume the presence of two FAMs at this geometry without any mutual interaction. Then Ap (r) between FAD and FAM is simply defined as follows 

Chemical Theory Beyond the Born-Oppenheimer Paradigm 

Below we describe the electronic reorganization solely in terms of the chemical terminology like sp hybridization, 7r-bonding, and so on without resort to the detailed numerical values of the density. (Note that once we refer to the magnitude of the coefficients of the atomic orbitals, the discussion may depend on the basis function chosen. By hybridization like sp and sp used below we simply mean the directionality or symmetry of the spatial distribution of an one-electron state as represented in the first-order density matrix.) 

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